A charging method of a lithium-ion secondary battery, by which a degree of deterioration of the lithium-ion secondary battery is detected from at least anyone of an internal resistance of the battery, a capacity to which the battery can be charged and the number of cycles of the charge then when the deterioration progresses, the battery is fully charged with a setting voltage set to be low, has been known (Patent Document 1).
However, a related art technique above has no awareness of problem about deterioration of a capacity balance between a positive electrode and a negative electrode, and does not perform a control according to each deterioration state of the positive electrode and the negative electrode. Because of this, in the related art technique, even in a case of capacity reduction of the positive electrode which does not intrinsically require decreasing a charge termination voltage, the charge termination voltage is set to be low. Thus, there is a problem of excessively limiting the charge of the battery.